Projection screen



Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE PROJECTION SCREEN Timothy N. Holden, Brooklyn, N. Y., assignor to James W. Decker No Drawing. Application August 2, 1933, Serial No. 683,319

6 Claims.

10 received so as to produce sharp, accurately defined images'and be devoid of any high light spots resulting from poor light dispersion.

It is still another object of the present invention to provide an improved translucent projection machine screen especially suited for rear projection which may with facility be produced uniform throughout and be free from striations or fiber shadows and the like.

It is still another object of the present invention to provide an improved translucent projection machine screen which is durable, comparatively odorless and comparatively immune to changes in atmospheric conditions either resulting from changes in temperature or changes in humidity.

It is still another object of the present invention to provide an improved translucent projection machine screen which can be produced at comparatively low cost and which is composed primarily of a support consisting of silk, artificial silk, or the like and a coating consisting of a mixture of boiled linseed oil and an alkali.

In the practice of the invention, either silk or artificial silk is used as the support, as. for instance, pussy willow silk, Chinese silk, Japanese silk, or rayon and the like.

Excellent results have been obtained when the support consisted either of pussy willow, Chinese or Japanese silk or rayon and this support was dipped in a mixture of boiled linseed oil, lead oxide, manganese dioxide and either sodium hydroxide or potassium hydroxide.

The mixture of linseed oil should preferably have the viscosity accompanying the oil when boiled down to a specific gravity of .9320 to .9350.

In the practice of the invention the support is first mounted upon a frame or base preferably rectangular in form and allowed to stand while stretched on this frame for at least five minutes to prevent distortion, whereupon the support while at room temperature is dipped into a bath also at room temperature consisting of linseed oil and an alkali, thereupon the support removed from the bath, the excess liquid allowed to flow of! and then, the support with the coating so acquired allowed to stand for one or two days. During this process of drying, it has been found that the coating is oxidized, turning from an initial yellowish color to a translucent, milky white.

From the foregoing it will thus appear that the actual coating process is conducted while the materials are in the cold state.

Depending upon the degree of translucency desired, the product, after the first coating and drying treatment, may again be immersed in the 10 bath and again dried, and this process repeated until the desired translucency is acquired.

For the screen of a stock quotation projection machine, it has been found that an excellent drying operation, and ordinarily, with not more than two such dipping and drying operations.

The bath is preferably composed of linseed oil, lead oxide, and manganese dioxide and an alkali such as sodium hydroxide, potassium hydroxide and the like.

The percentage by weight of these several ingredients is preferably as follows:

Parts by weight product is produced with a single dipping and 15 Linseed oil 97.8

Lead oxide .1 Manganese dioxide .1 Sodium hydroxide 2.0

The linseed oil, lead oxide and manganese dioxide are preferably boiled at a temperature of five hundred degrees to six hundred degrees Fahrenheit in advance to produce the desired viscosity, preferably that accompanying a specific nesses of cheese cloth and thereupon be ready for use as the bath.

Thereupon, the silk or rayon having been stretched across the frame as aforesaid, for at least five minutes to prevent distortion,- will be dipped into the solution, the excess liquid allowed to flow off and the silk or rayon while still stretched on the frame then allowed to stand for approximately forty-eight hours, during which time it will appear that the coating has been oxidized and the coated material satisfactorily treated ready for use. During this oxidizing process, it will also appear that the original yellowish color of the dipped silk or rayon and the transparent character of the same will have changed, and the material now be translucent, have a milky white color and have a dull finish.

It has also been found that the number of treatments to which the fabric is to be subjected depends largely upon the thickness and mesh of the fabric and finally to the ultimate use intended for the same.

It is of course also obvious that due to its waterproof characteristic the improved fabric produced by the present invention is not limited in its use for projection work but can also be used in'hospitals and the like.

The word -mixture has been used to define the liquid formed when boiling the linseed oil with the lead oxide and manganese dioxide, and has also been used to define the liquid formed when adding the alkali to the boiled linseed oil. It is obvious that there is some chemical reaction between the several elements although it is difficult to determine and in view thereof it is not intended that the word mixture when here used in defining this liquid merely connotes a true mechanical mixture, but that it is intended to cover either a mechanical mixture, a chemical combination or both.

It is obvious that various changes and modifications may be made .to the details of construction of the product and to the steps of the process without departing from the general spirit of the invention as set forth in the appended claims.

In practicing my invention, I have also found that the resulting material or screen can be immersed in a dye bath or the dye applied only to one face of the material to impart the color desired for the use intended. Excellent results in this connection have been obtained when applying tintex or aniline dye.

I claim:

1. The process of forming an improved material consisting in preparing the liquid for a bath by boiling a mixture of linseed oil and a drier to a heavy viscosity, allowing the liquid to cool, adding hydroxide to the resulting liquid, allowing a soap percentage to precipitate, filtering ofl the soap precipitate, dipping the silk or the artificial silk fabric in the decanted liquid, and allowing the fabric to dry.

2. The process of forming a projection screen consisting in preparing consisting in preparing a liquid for a bath by boiling a mixture of linseed oil, manganese dioxide, allowing the liquid to cool, adding sodium hydroxide to the resulting liquid, allowing a soap percentage toprecipitate, filtering of! the soap precipitate, dipping a rayon fabric in the decanted liquid, removing the fabric from the liquid, and allowing the fabricto dry.

3. The process of forming a projection screen consisting in preparing a liquid for a bath by boiling at a temperature of five hundred to six hundred degrees Fahrenheit, a mixture of linseed oil and a drier, allowing the liquid to cool, adding a hydroxide at room temperature, allowing a soap percentage to precipitate, filtering off the soap precipitate, dipping a silk or artificial silk fabric in the decanted liquid, removing the fabric from the liquid, and allowing the fabric to dry.

4. The process consisting in preparing a boiling for approximately one hour linseed oil and a drier, allowing the liquid to cool, adding a hydroxide, allowing the resulting liquid to stand for approximately four days, to precipitate the soap formed, filtering off the soap precipitate, dipping a silk or artificial silk fabric in the decanted liquid, removing the fabric from the liquid, and allowing the fabric to dry for approximately forty-eight hours.

5. The process of forming a projection screen a boiled liquid, composed of 97.8 parts by weight of linseed oil, 0.2 part by weight of a drier, and 2.0 parts by weightof a hydroxide, allowing the resulting liquid to stand to precipitate the soap formed thereby, filtering off the soap precipitate, dipping a silk or artificial silk fabric in the decanted liquid, removing the fabric from the liquid, and allowing the fabric to dry.

6. The process of forming an improved material consisting in preparing the liquid for a bath by boiling a mixture of linseed oil and a drier to a heavy viscosity, allowing the liquid to cool, adding a hydroxide to the resulting liquid, allowing a soap percentage to precipitate, filtering of! the soap precipitate, dipping the silk or the artificial silk fabric in the decanted liquid, allowing the fabric to dry, and thereupon applying a dye of the color desired either to one or faces of the resulting fabric.

'I'DIOTHY N. HOLDEN.

of forming a projection screen liquid for a bath by a mixture oi!- lead oxide and both 

